1. Field of the Invention
The present invention relates to a power supply apparatus and method for a hybrid vehicle, and more particularly, to a power supply apparatus and method for a hybrid vehicle in which a power conversion device and an energy storage device are integrated in order to reduce a size and production cost of the power supply apparatus.
2. Discussion of Related Art
In general, a 48V Mild Hybrid Electric Vehicle (HEV) is a hybrid vehicle made for the purpose of improving fuel efficiency and reducing carbon dioxide emission by stopping the engine when the vehicle is stopped, performing regenerative braking when the vehicle decelerates, and performing engine torque assistance when the vehicle accelerates.
Compared with an existing HEV, a 48V Mild HEV may additionally include a hybrid function by replacing an alternator and adding a 48V power device without changing a vehicle body, thus improving fuel efficiency at a low cost.
Since the body of such a 48V Mild HEV cannot be changed, the size and mountability are very important factors in developing vehicle components and implementing a system.
In a conventional 48V system installed in such a 48 Mild HEV, a power conversion device and an energy storage device are separated from each other.
For example, FIG. 1 is a view showing a configuration of a conventional electric system installed in a 48V Mild HEY. As shown in FIG. 1, the conventional electric system installed in the 48V Mild HEV includes a 48V battery 10, a 12V battery 20, a converter 30, and an inverter combined with an integrated starter-generator (ISG) (ISG/inverter) 40.
When an engine is started, the 48V battery 10 supplies 48V DC power to the inverter 40.
When the engine is started, the 12V battery 20 supplies 12V DC power to the converter 30.
The converter 30 converts the 12V DC power supplied from the 12V battery 20 into 48V DC power when the engine is started, and then supplies the converted 48V DC power to the inverter 40.
The inverter 40 converts the 48V DC power supplied from the 48V battery 10 and the 48V DC power supplied from the converter 30 into 48V AC power when the engine is started, and then supplies the converted 48V AC power to the ISG
In addition, when the engine generates power, the inverter 40 converts the AC power supplied from the ISG into the 48V DC power, and then supplies the converted 48V DC power to the 48V battery 10 and the converter 30.
The converter 30 converts the 48V DC power supplied from the inverter 40 into 12V DC power when the engine generates power, and then supplies the converted 12V DC power to the 12V battery 20.
The 48V battery 10 stores the 48V DC power supplied from the inverter 40 when the engine generates power.
The 12V battery 20 stores the 12V DC power supplied from the converter 30 when the engine generates power.
Here, the inverter 40 and the converter 30 are included in a power conversion device, and the 48V battery 10 and the 12V battery 20 are included in an energy storage device.
As described above, the conventional electric system installed in the 48V Mild HEV has the power conversion device and the energy storage device, which are separated from each other, and thus has difficulties in reducing a size and production cost of the 48V Mild HEY.